If the batteries are changed too quickly so that the thermostat does not recognize the change, the battery status remains at the old level.
Please remove the batteries and wait approx. 30 seconds.
After inserting the new batteries, a red wrench appears in the display. Press and hold the handwheel for 3 seconds, then F11 appears in the display. Press the handwheel again 1x briefly, then F12 is displayed, the heating thermostat is recalibrated and is ready for operation. A new teach-in in the app is not necessary!